The present invention relates to a plant for the dynamometric braking of heat engines under test, acceptance test or experimental test or the like and the simultaneous recovery of energy produced by such engines, by conversion of such energy into alternating electrical current, by means of an accumulation and regulation unit which provides for regulating the circulating flow while maintaining the alternator always on the grid under whatever circumstances, even in the absence of energy produced by the heat engines under test.
It is known that the firms which construct heat engines of small and medium capacity, for example from 20 to 300 kW, keep permanently running a certain number of engines for effecting running-in and acceptance or for experimental runs of long duration.
Although engines of different outputs and having different operational sequences are adjacent to one another on test beds, the total power used in said tests is frequently considerable, even amounting to some hundreds of kW, and it is generally lost in the usual dynamometric brakes or is used in part in the form of heat with a limited possibility of utilization at low efficiency.
The recovery of the mechanical power produced by the engines under test, in the form of electrical energy, which is the most desirable form, has proved to be difficult on account of the discontinuity of energy production by the engines under test due both to the rotational speed and torque of each engine and to the number of engines simultaneously in operation, with the result that it proves impossible to achieve a recovery in the form of practically useful electrical energy. In fact dynamometric brakes with wound rotor, either for direct current or for alternating current are used, but they present respectively notable problems of control of the voltage or of parallel coupling, which hinder their use. Also proposed have been circuits of the hydraulic type employing dynamometric brakes with hydraulic pumps associated with hydraulic motors or turbines for connection to an alternator, but such plants also have proved to be very costly and of limited use, in that it is necessary to make use of pumps having a very flat characteristic accompanied by loss of efficiency and the necessity of using enormous delivery rates of water involving prohibitive costs and bulk.